libcamera: stream: Add Stream memory type

Define the memory type a Stream uses and allow application to set it
through the associated StreamConfiguration.

A Stream can use either internal or external memory allocation methods,
depending on where the data produced by the stream is actually saved.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/stream.h

@@ -35,6 +35,11 @@ private:
 	std::map<unsigned int, std::vector<SizeRange>> formats_;
 };
 
+enum MemoryType {
+	InternalMemory,
+	ExternalMemory,
+};
+
 struct StreamConfiguration {
 	StreamConfiguration();
 	StreamConfiguration(const StreamFormats &formats);
@@ -42,6 +47,7 @@ struct StreamConfiguration {
 	unsigned int pixelFormat;
 	Size size;
 
+	MemoryType memoryType;
 	unsigned int bufferCount;
 
 	Stream *stream() const { return stream_; }
@@ -73,15 +79,17 @@ public:
 	BufferPool &bufferPool() { return bufferPool_; }
 	std::vector<BufferMemory> &buffers() { return bufferPool_.buffers(); }
 	const StreamConfiguration &configuration() const { return configuration_; }
+	MemoryType memoryType() const { return memoryType_; }
 
 protected:
 	friend class Camera;
 
-	void createBuffers(unsigned int count);
+	void createBuffers(MemoryType memory, unsigned int count);
 	void destroyBuffers();
 
 	BufferPool bufferPool_;
 	StreamConfiguration configuration_;
+	MemoryType memoryType_;
 };
 
 } /* namespace libcamera */

src/libcamera/camera.cpp

@@ -683,7 +683,7 @@ int Camera::configure(CameraConfiguration *config)
 		 * Allocate buffer objects in the pool.
 		 * Memory will be allocated and assigned later.
 		 */
-		stream->createBuffers(cfg.bufferCount);
+		stream->createBuffers(cfg.memoryType, cfg.bufferCount);
 	}
 
 	state_ = CameraConfigured;

src/libcamera/stream.cpp

@@ -263,6 +263,17 @@ SizeRange StreamFormats::range(unsigned int pixelformat) const
 	return range;
 }
 
+/**
+ * \enum MemoryType
+ * \brief Define the memory type used by a Stream
+ * \var MemoryType::InternalMemory
+ * The Stream uses memory allocated internally by the library and exported to
+ * applications.
+ * \var MemoryType::ExternalMemory
+ * The Stream uses memory allocated externally by application and imported in
+ * the library.
+ */
+
 /**
  * \struct StreamConfiguration
  * \brief Configuration parameters for a stream
@@ -276,7 +287,7 @@ SizeRange StreamFormats::range(unsigned int pixelformat) const
  * handlers provied StreamFormats.
  */
 StreamConfiguration::StreamConfiguration()
-	: stream_(nullptr)
+	: memoryType(InternalMemory), stream_(nullptr)
 {
 }
 
@@ -284,7 +295,7 @@ StreamConfiguration::StreamConfiguration()
  * \brief Construct a configuration with stream formats
  */
 StreamConfiguration::StreamConfiguration(const StreamFormats &formats)
-	: stream_(nullptr), formats_(formats)
+	: memoryType(InternalMemory), stream_(nullptr), formats_(formats)
 {
 }
 
@@ -301,6 +312,11 @@ StreamConfiguration::StreamConfiguration(const StreamFormats &formats)
  * format described in V4L2 using the V4L2_PIX_FMT_* definitions.
  */
 
+/**
+ * \var StreamConfiguration::memoryType
+ * \brief The memory type the stream shall use
+ */
+
 /**
  * \var StreamConfiguration::bufferCount
  * \brief Requested number of buffers to allocate for the stream
@@ -454,18 +470,26 @@ std::unique_ptr<Buffer> Stream::createBuffer(unsigned int index)
  * \return The active configuration of the stream
  */
 
+/**
+ * \fn Stream::memoryType()
+ * \brief Retrieve the stream memory type
+ * \return The memory type used by the stream
+ */
+
 /**
  * \brief Create buffers for the stream
  * \param[in] count The number of buffers to create
+ * \param[in] memory The stream memory type
  *
  * Create \a count empty buffers in the Stream's buffer pool.
  */
-void Stream::createBuffers(unsigned int count)
+void Stream::createBuffers(MemoryType memory, unsigned int count)
 {
 	destroyBuffers();
 	if (count == 0)
 		return;
 
+	memoryType_ = memory;
 	bufferPool_.createBuffers(count);
 }
 
@@ -497,4 +521,9 @@ void Stream::destroyBuffers()
  * next call to Camera::configure() regardless of if it includes the stream.
  */
 
+/**
+ * \var Stream::memoryType_
+ * \brief The stream memory type
+ */
+
 } /* namespace libcamera */